摘要:

SUMMARYColony development ofErysiphe graminisf.sp.avenaerace 2 was studied on detached leaf segments of a range ofAvenahosts with different levels of resistance, none of which possesses known specific gene resistance to this race. Resistance affected the length attained by mature primary haustoria, and also colony size as assessed by numbers of haustoria and conidiophores produced per colony 5 days after inoculation. A more accurate assessment of the size of mature haustoria was provided by the total length of their digitate processes. At the primary haustorium stage resistance affected not only haustorial size, but also haustorial efficiency measured as colony growth per unit size. Adult plant resistance of some hosts decreased haustorial size and/or efficiency in colonies on the fifth in comparison with the first formed leaf.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1978.tb00692.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

SUMMARYFrom two field samples of crown rust, isolates were selected for increased aggressiveness on four of 10 resistant perennial ryegrass clonal lines. Two lines which were formerly highly resistant became highly susceptible to the selected isolates but two which were formerly moderately resistant became only moderately susceptible. Thus, moderate resistance, although no less likely to be race‐specific, was more stable than a high level of resistance.Cultures from highly resistant lines did not show increased aggressiveness on the varieties from which the resistant lines had been selected; hence individual genes of major effect were unimportant in determining varietal resistance. In contrast, cultures from moderately resistant lines were substantially more aggressive on their corresponding varieties. Three varieties contained many genes which tended to buffer changes in virulence of the rus

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1978.tb00693.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

SUMMARYGlasshouse and field experiments were conducted to investigate the effects of sowing both untreated and pre‐germinated seeds, with or without a gel carrier, and also pelleted seeds into soils of different moisture contents and at different temperatures on seedling emergence of lettuce cvs Cobham Green and Avondefiance.Pre‐germinated seeds with radicles 1–2 mm long gave, on average, 15 and 4% higher final percentage emergence than untreated and pelleted seeds respectively. Sowing pre‐germinated seeds having radicles longer than 2 mm gave more variable levels of emergence and often reduced emergence, particularly when they were sown into dry or drying seedbeds. Increasing the rate of gel carrier from 0 to 30 ml m_1of row reduced emergence progressively from 67 to 30%. Pre‐germinated seeds emerged 2–5 and 3‐0 days earlier than untreated and pelleted seeds, respectively, at a soil temperature of 10oC; at 15oC the corresponding figures were 0–5 and 3–5 days. Sowing pre‐germinated seeds reduced the spread (i.e. variability) of emergence by an average of 37 and 47% compared with untreated and pelleted

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1978.tb00694.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

SUMMARYThe effect of transferring onion bulbs from low to high temperatures during storage was investigated. It was found that the later transfer was made the lower was the weight loss per bulb but the greater the loss from sprouting. The lowest total loss observed was 37% by May following transfer in January.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1978.tb00695.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1978.tb00696.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY